High blood glucose after lunch is the only indication of abnormal blood glucose metabolism, and the causes of the corresponding conditions mainly include over-eating, under-consumption, and under-dose of medication. 1. Eating too much: Generally, if you eat too much at noon, it will lead to a large amount of glucose into the blood, causing blood sugar to rise. 2. Consumption is too little: after eating at noon, because of the lack of exercise, the body’s consumption of blood glucose is reduced, which can also lead to increased blood glucose performance. 3. Insufficient medication: If you are a diabetic patient, during the period of medication control, it is possible that it is related to insufficient medication, and the corresponding condition will also lead to a rise in blood sugar. Blood sugar instability after lunch, and if accompanied by symptoms related to diabetes, you need to consult a doctor in time to observe, through the examination to confirm the diagnosis of the condition, under the guidance of the clinician for standardized treatment.